Paint within 1hr after applying primer, or wait 24 hrs?

I'm using Rust-oleum Ultra Cover 2x primer. I've already done a few rounds of primer and light sanding, and am ready to apply the topcoat. The primer says to apply to topcoat within 1 hour or after 24 hours. Although the rocket does not need any more primer, I'm wondering if there are any advantages to applying another light coat of primer, and then applying the top coat within the 1st hour. Will this help the topcoat adhere to the primer better?

cjp987 said:

I'm using Rust-oleum Ultra Cover 2x primer. I've already done a few rounds of primer and light sanding, and am ready to apply the topcoat. The primer says to apply to topcoat within 1 hour or after 24 hours. Although the rocket does not need any more primer, I'm wondering if there are any advantages to applying another light coat of primer, and then applying the top coat within the 1st hour. Will this help the topcoat adhere to the primer better?

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If you want a great looking finish, you need to sand your primer... I hit mine with 220 grit followed up with 400 grit, usually after dunking the sandpaper into a bowl of water and shaking off the excess... this "damp sanding" gives a great finish and keeps the paper from clogging up. Now, I usually use the regular Rusto primer for this, I haven't bothered with the Painter's Touch stuff. But basically any imperfections you can see in the primered finish at this point will be MAGNIFIED in the final color coats.

SO, if you're happy with the paint job as-is, then yeah, put your topcoat on within an hour. If you see any imperfections and want a beautiful finish, NOW is the time to sand them out; the painting will wait til tomorrow...

Later and good luck! OL JR

luke strawwalker said:

If you want a great looking finish, you need to sand your primer... I hit mine with 220 grit followed up with 400 grit, usually after dunking the sandpaper into a bowl of water and shaking off the excess... this "damp sanding" gives a great finish and keeps the paper from clogging up. Now, I usually use the regular Rusto primer for this, I haven't bothered with the Painter's Touch stuff. But basically any imperfections you can see in the primered finish at this point will be MAGNIFIED in the final color coats.

SO, if you're happy with the paint job as-is, then yeah, put your topcoat on within an hour. If you see any imperfections and want a beautiful finish, NOW is the time to sand them out; the painting will wait til tomorrow...

Later and good luck! OL JR

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TRUST WHAT HE SAID---!!!!!--- The paint tends to rewet the primer and cause---hmmmm--micro shrinkage--- You need to get the surface done and without flaws and give it time to breath--24-48 hrs is a good guess---I've done stuff and a month later it looks like hell because it dried and shrank--do not rush the primer or paint!!!!! There are lots of days to launch !Well , not so much with the Texas wind, but you get my point.---H

I've already primed and sanded to the point of getting rid of imperfections, and of course am well past 24 hours since the last primer coat. My question is whether I can expect the topcoat to do a better job of adhering to the primer if I apply the topcoat within 1 hour of priming, and therefore I should apply another light primer coat before doing the topcoat. If I see any imperfections with this final primer coat, I'd certainly sand them out before applying the topcoat. It should be possible to do that and still get the topcoat applied within 1 hour (usually it's sandable after 30 minutes).

cjp987 said:

I've already primed and sanded to the point of getting rid of imperfections, and of course am well past 24 hours since the last primer coat. My question is whether I can expect the topcoat to do a better job of adhering to the primer if I apply the topcoat within 1 hour of priming, and therefore I should apply another light primer coat before doing the topcoat. If I see any imperfections with this final primer coat, I'd certainly sand them out before applying the topcoat. It should be possible to do that and still get the topcoat applied within 1 hour (usually it's sandable after 30 minutes).

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At least from my experience you don't have to worry about the paint grabbing the primer better because it's still --not dry-- or still tacky---. Does'nt work that way---The paint will adhere to any surface that is well prepared and does not need the primer to be soft. Sounds like you are concerned with a chemical bond as opposed to a physical bond---your over thinking the process---A lite sanding of the primer---after it's dry and ready-- then spray your top coat--- do not rush the process---like I've said before--It's like fishing--when you think your working your bait slow---your going too fast---SLOW IT DOWN !

hornet driver said:

At least from my experience you don't have to worry about the paint grabbing the primer better because it's still --not dry-- or still tacky---. Does'nt work that way---The paint will adhere to any surface that is well prepared and does not need the primer to be soft. Sounds like you are concerned with a chemical bond as opposed to a physical bond---

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Yes, that's basically what I was thinking. I thought maybe the topcoat would adhere better to a fresh primer coat, and that the fresh primer coat would adhere to the underlying cured primer coat better than the top coat does.

your over thinking the process---A lite sanding of the primer---after it's dry and ready-- then spray your top coat--- do not rush the process---like I've said before--It's like fishing--when you think your working your bait slow---your going too fast---SLOW IT DOWN !

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Ok. I only feel like I'm rushing if I try to topcoat within 1 hour, but in almost all cases I wait 24 hrs, do light sanding, and then topcoat if I'm happy with how the primer coat looks. Initially I start with 2 or 3 primer coats within an hour, let it sit 24 hrs, sand, and then decide how much additional priming is still needed and go from there.

cjp987 said:

I've already primed and sanded to the point of getting rid of imperfections, and of course am well past 24 hours since the last primer coat. My question is whether I can expect the topcoat to do a better job of adhering to the primer if I apply the topcoat within 1 hour of priming, and therefore I should apply another light primer coat before doing the topcoat. If I see any imperfections with this final primer coat, I'd certainly sand them out before applying the topcoat. It should be possible to do that and still get the topcoat applied within 1 hour (usually it's sandable after 30 minutes).

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I don't see any point to applying MORE primer on top of an already finished (sanded down to the final desired result) surface. At this point, I'd make sure that the primer has outgassed (no longer smells like "wet paint" when you put your nose to it and sniff), tack it off with a clean tack rag (to remove dust and fingerprints) and then hit it with the lightest color coats, working to darker colors (if you're doing multiple colors anyway).

Remember that primer has a LOT of solids in it, WAY more than color pigments in the final color coats. Odds are that another coat of primer won't lay down as smooth and pretty as your sanded surface, meaning it won't look as good... and every extra application AFTER sanding is ANOTHER chance of something going wrong, and picking up a drip, sag, or run, or bugs in the finish, or something else that will make you say naughty words and have to go back and resand the offending area...

Sometimes less is more...

Later and good luck! OL JR

cjp987 said:

Yes, that's basically what I was thinking. I thought maybe the topcoat would adhere better to a fresh primer coat, and that the fresh primer coat would adhere to the underlying cured primer coat better than the top coat does.

Ok. I only feel like I'm rushing if I try to topcoat within 1 hour, but in almost all cases I wait 24 hrs, do light sanding, and then topcoat if I'm happy with how the primer coat looks. Initially I start with 2 or 3 primer coats within an hour, let it sit 24 hrs, sand, and then decide how much additional priming is still needed and go from there.

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Yep... sounds like you're on the right track...

I have to say, I don't usually wait that long between priming and sanding... I sometimes will sand within a couple hours or so of priming, depending on the climatic conditions when I'm priming... (hot windy Texas summers come in handy for that, but oftentimes I can do much the same even in the milder weather of spring or fall... just depends-- One time in Indiana I had to wait until late evening to sand after priming mid-morning... much cooler up there in the summer...)

Later and good luck! OL JR